Question #6fb36

1 Answer
Nov 6, 2017

1.99 xx 10^-18 " J"1.99×1018 J

Explanation:

We know that lambda nu = cλν=c and E = h nuE=hν, where

  • lambdaλ is wavelength ("m")(m)
  • nuν is frequency ("s"^-1 (s1 or "Hz")Hz)
  • cc is the speed of light, 2.998 xx 10^8 " m/s"2.998×108 m/s
  • hh is Planck's constant, 6.626 xx 10^-34 " J" * "s"6.626×1034 Js

We could directly use E = h nuE=hν, but since we don't know nuν, we can solve for it in the first equation and substitute.

lambda nu = cλν=c

nu = c/lambdaν=cλ

So, E = (hc) / lambdaE=hcλ.

The given wavelength is "100. nm"100. nm. Convert this to meters.

lambda = 100. cancel("nm") xx ("1 m") / ("10"^9 cancel("nm") )= 10.0 ^-7 " m"

E_("photon") = (hc) / lambda

E_("photon") = (6.626 xx 10^-34 " J" * "s" * 2.998 xx 10^8 " m/s") / (10.0 ^-7 " m")

E_("photon") = 1.99 xx 10^-18 " J"